For a long time now, various feeders exist in document processing systems for delivering documents such as sheets, letters, postcards, checks into these systems for further processing. These feeders generally include a delivery portion and a destacking or singulating portion. The flat items are typically placed onto the delivery portion and delivered to the singulating portion for further processing in a sorting section. Typically operators manually load the items taken from storage boxes, trays, tubs, carts or hampers into the delivery portion at the beginning of the operational cycle. They usually go on loading the items on the fly while the system is running. The items are picked off the stack by a singulating module which feeds a reading module with them one at a time. The optical character or bar code reader reads some indicia printed on the item (e.g. zip code) and generates a signal representative thereof. A computer then processes this signal for directing and diverting this individual item to a designated sort pocket in the stacking section of the system.
U.S. Pat. No. 4,595,188 relates to a speed control system for an envelope feeding mechanism used to feed envelopes to a pickoff device in a high speed mail sorting machine. The feeding mechanism includes a pair of toothed belts which convey the envelopes along an inclined surface. The side edges of the envelopes are received by a third toothed belt which is driven at an elevated position along a side panel. The belts are driven by a multiple speed electric motor controlled by electronic circuitry which automatically decrements or increments the motor speed if the envelopes are bunched together too tightly or too loosely. If the speed is decremented and the envelopes are still tightly bunched, the drive motor is stopped by a shutoff circuit which operates independently of the speed control circuit.
U.S. Pat. No. 6,318,717 is directed to a singulator for feeding documents one at a time onto the transport of a processing machine. The singulator includes a pick-off means and a stripper means for preventing multi-feeds of documents. The stripper means is comprised of two independent stripper assemblies which are mounted one above the other. Each assembly is comprised of an arm which is rotatably mounted to the machine at one end and which has a means at the other end for engaging any multi-fed documents. Each stripper assembly has basically the same structure except the arm of one stripper assembly is shorter than the arm of the other assembly whereby the assemblies contact a multi-fed document at different points.
U.S. Pat. No. 6,511,062 concerns an apparatus and method for controlling the presentation of articles to the singulation head of a system for singulating a stack of edge-mounted articles, for example mixed mail, which mechanism senses the instantaneous pressure at which the lead article of the stack is pressed against the singulation head. A feedback control may be provided responsive to a difference between detected instantaneous pressure and a desired target pressure for controlling at least one drive member in a manner so as to reduce such difference. Where there is a pick window of instantaneous pressure at which singulation can be effectively performed, a control may also be provided to inhibit operation of the singulation head when the instantaneous pressure is outside the pick window. Two vertically spaced pressure sensors may be provided on the singulation head to detect the angle at which the lead article is presented to the head and controls may be provided for the drive mechanism(s) to reduce the difference between the instantaneous angle detected and an optimum angle for singulation and/or to inhibit operation of the singulation head when the instantaneous angle is outside of a range where singulation may be effectively performed. The sensor preferably includes a lever extending from the surface of the singulation head which is moved by a distance dependant on the pressure applied thereto. A servo motor may be connected to the lever to apply a bias pressure thereto which bias pressure is determined by a control signal applied to the motor. The sensor may also include a position encoder generating an output indicative of lever position.
U.S. Pat. No. 7,195,236 discloses automated induction systems and methods for mail and/or other objects. In some embodiments, a system for automated loading of a side-by-side stack of thin objects to a feeder is provided. The system can include, e.g.: a) a transporter having a transport surface upon which a side-by-side stack of thin objects can be conveyed; b) a carrier, configured to carry a side-by-side stack of thin objects, over the transport surface; c) a pusher over the transport surface; d) the pusher and the carrier being movable relative to one another between a first position in which the pusher is inside the carrier behind a side-by-side stack of thin objects on the carrier and a second position in which the pusher is laterally displaced from the carrier, such that the side-by-side stack of thin objects on the carrier is laterally slid off of the carrier by the pusher.
While these types of feeders generally work rather well, those skilled in the art will admit they can still experience significant multi-feed issues in sorting large batches of flat items or mixed flat articles with a size and/or thickness that can significantly vary within the batch. The above prior art documents propose good solutions which are however sophisticated, e.g. involving speed control, pressure control or orientation angle control. Since it highly matters to avoid as much as possible a decrease in throughput, an increase in multi-feeds, an increase in damage, jamming and/or other problems, any improvement in the reduction of multi-feeds of flat items is sought after.
Accordingly, a need exists for a feeding apparatus that can overcome, among other things, the above and/or other issues with existing systems, in a manner as simple and efficient as possible.